OBJECTIVETo explore the feasibility of magnetic resonance cell imaging technology by using polyethylene imine (PEI)-coated magnetic nanoparticles of Fe₄O₄ (PEI-Fe₄O₄-MNPs) to track cell biology behavior.

METHODSEndocytic PEI-Fe₄O₄-MNPs in SHI-1 cells were observed by transmission electron microscopy (TEM) . Iron contents of nano-labeled cells were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and Prussian blue staining. The proliferation ability of labeled cells was detected by cell counting kit-8 (CCK-8) assay; the differentiation and colony-forming abilities were also observed. SHI-1 cells without endocytosing PEI-Fe₄O₄-MNPs were used as control.

RESULTSOur data showed that PEI-Fe₄O₄-MNPs could label SHI-1 cells. The labeling efficiency depended on the nanoparticles' concentration and the duration of cells treating. Inhibition rates of SHI-1cells labeled by 60-100 μg Fe/ml PEI-Fe₄O₄-MNPs were much higher than of 5-50 μg Fe/ml ones following treating by 5-100 μg Fe/ml PEI-Fe₄O₄-MNPs for 48 hrs. The expressions of CD11b and CD14 were (78.4±18.5)% and (18.7±2.9)% in control vs (83.3±14.2)% and (20.4±2.1)% in cells fractions treated by 30 μg Fe/ml PEI-Fe₄O₄-MNPs. Clony-forming rates of SHI-1 cells labeled by 0, 20 , 50 μg Fe/ml PEI-Fe₄O₄-MNPs were (25.20±7.22)%, (25.93±13.15)%, (23.37±9.33)%, respectively. Differentiation and colony-forming potentials of labeled cells were similar with control in the certain range of PEI-Fe₄O₄-MNPs concentration.

CONCLUSIONSHI-1 cells were efficiently labeled by PEI-Fe₄O₄-MNPs with well biocompatibilities in proper range of concentration, the latter could be coupled with magnetic resonance imaging (MRI) to track cells in vivo.